Display screen or portion thereof with an animated graphical user interface



FIG. 1 is a front view of the first image of a display screen or portion thereof with an animated graphical user interface showing the new design;

FIG. 2 is a second image in a sequence thereof;

FIG. 3 is a third image in a sequence thereof;

FIG. 4 is a fourth image in a sequence thereof;

FIG. 5 is a fifth image in a sequence thereof; and,

FIG. 6 is a sixth image in a sequence thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-6.

The outermost broken lines illustrate the display screen or portion thereof and form no part of the claimed design. The remaining evenly spaced broken lines and the diagonal broken lines illustrate portions of the graphical user interface and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an animated graphical user interface, as shown and described. 